Pleasure gardens, or horti, offered elite citizens of ancient Rome a retreat from the noise and grime of the city, where they could take their leisure and even conduct business amid lovely landscaping, architecture, and sculpture. One of the most important and beautiful of these gardens was the horti Sallustiani, originally developed by the Roman historian Sallust at the end of the first century B.C. and later possessed and perfected by a series of Roman emperors. Though now irrevocably altered by two millennia of human history, the Gardens of Sallust endure as a memory...